Electrolytic production of metals



March 21 1939.

e. J AEGERO ELECTROLYTIC PRODUCTION OF METALS Filed Nov. 24, 1936 Elma/whom uaiav Jqqr Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE ELECTROLYTIC PRODUCTION OF IVIETALS Application November 24, 1936, Serial No. 112,615 In Germany December 12, 1935 6 Claims.

My invention relates to the production of metals obtained in the solid, preferably crystallised form, by the electrolysis of suitable molten metal salts, and more particularly to the production of beryllium and thorium, furthermore aluminium, chromium, manganese, iron and so forth.

In carrying out such processes the metals are obtained partly in the coarsely crystalline form,

10 partly in the finely crystalline form and partly in the form of powder. Frequently, they form a kind of furry coating on the cathode. If an attempt is made to scrape off and collect the deposited metal, the latter is dispersed in the molten electrolyte and cannot be collected. In such cases, the method generally adopted for recovering the metal is to allow the electrolyte to solidify and to obtain the metal present therein by steps such aswashing out the electrolyte and so forth. This method of working involves dis advantages, such as interruptions in the operation, loss of electrolyte or danger of oxidation in the case of finely divided metal.

According to my invention, the electrolysis is carried out with the use of two or more electrolysing vessels, preferably of like construction, and with'the step that electrolysis is first effected in one vessel, then after deposition of a sumcient quantity of metal, the molten electrolyteis transferred to the second vessel, where it is electrolysed further, if necessarywith the addition of fresh electrolyte, theinetal left in the first vessel is recovered, the electrolyte is returned from vessel 2 to vessel [again after completion of the v electrolysis, andis there electrolysed further, if

necessary after theaddition of. fresh electrolyte, and so forth;

In this method,"dfli wainngifit is possible to conduct as favourably as possible the'electrolysis' which takes place in eachcase. It may be interrupted before disturbances occur, such as the formation of bridges or the accumulation of metal on the bottom of the vessel, and the electrolyte may be electrolysed further immediately in the molten state in the adjacent vessel while practically avoiding any loss of heat. It has been found that it is possible to draw'ofl the molten- 'made by the interposition of sieves or the like to ensure that the melt will be free from metallic particles when it passes into the adjacent electrolysing vessel. The metal left behind in the emptied vessel or retained by the sieve may be 5 freed in a very simple manner, for example, by washing, from the small quantities of electrolyte still adhering to it, and may be recovered in a pure form. The electrolysing process, according to the foregoing, may in practice be carried out 10 in acontinuous operation free from disturbances in the simplest possible manner, and at the same time considerable advantages may be secured.

In place of two electrolysing vessels, a larger number may also be employed, in which case, if 15 desired, receiving or collecting vessels, not constructed as electrolytic cells but expediently protected against loss of heat, may be provided for the electrolyte. I My invention win be explained by way of an 29 example with reference to the accompanying drawing:

Figure 1 shows an apparatus comprising two adjacent electrolysing vessels I and II, the bottoms whereof in the constructional example are '25 made sloping in order to facilitate drawing off the electrolytes as completely as possible. The wall a v of the vessel at the same time forms the cathode and at b is shown the centrally disposed anode. The electrolysing vessel is provided with a cover fitting in a good air-tight manner.

For transferring the electrolyte from one vessel to the other, use is made of a siphon-like pipe d,

the longer limb whereof if desired may be wid- 35 ened or flared somewhat at the lower end and may be closed by a sieve in order to prevent particles of metal from being carried away while the electrolyte isbei'ng-"drawn oil. The anode b is expediently suspended from the cover 0, the

siphon pipe 11 may be rigidly secured to the cover 0 or may be joined on to the electrolysing vessel by means of a special connecting piece in a good fluid-tight manner.

The cover 0 equipped with the anode b and 45 the siphon pipe 11 may if desired be employed for both vessels. The transfer of the electrolyte from one vessel to the other may be efiected by forcing an inert compressed gas, for example hydrogen or nitrogen, through a connection (not shown) into the upper part of the cell which is to be emptied, or by producing a. vacuum in the cell which is tobe filled and thereby aspirating the electrolyte into said cell. In the first-men.-

tioned case, the cell to be filled may be without cover, but in the second case of course the said cell must be closed in a fluid-tight manner.

Figure 2 shows a constructional form in which the electrolyzing vessels I and II are arranged one above the other. The cells are provided on the bottom with branches e adapted to be closed for example by valves, but closure may also be effected for example by surrounding the branch with a cooling jacket I, so that upon passing cooling liquid therethrough, solidification of the melt will take place in the branch. Furthermore, a sieve g is expediently provided in the branch.

Figure 3 shows a constructional form of the apparatus according to Figure 2 in which, between the electrolyzing vesselI and electrolyzing vessel II, there is provided a vessel h in which is located a perforated drum 5 for collecting the metal. Expediently, the perforated drum i is adapted to be operated as a centrifuge. In the constructional form, an insertion piece It is provided for enabling the drum to be inserted in a centrifuge- By centrifuging, it is possible in a very simple manner to free the metal collected in the perforated drum from any fused salt still adhering to the metal, and if desired also to wash it in the drum.

Figure 4 shows a constructional form in which the electrolyzing vessels I and II are altered in position by means of a rotatable suspension device l in such a manner that, after completion of the electrolysis in the upper vessel and drawing off the electrolyte into the lower vessel, the lower vessel is moved upwardly for continuing the electrolysis and the upper vessel is moveddownwardly for recovering the metal.

The electrolyzing vessels may of course also be constructed so that the wall of the vessel does not act as cathode but a special cathode is pro-' vided, for example in such a manner that the centrally disposed anode is surrounded by an annular or casing-like cathode.

The process is carried out for example as follows: 7

Electrolyzing vessel I is charged with the electrolyte and subjected to electrolysis. When sufficient metal has been deposited, the salt melt is transferred to electrolyzing vessel 11, where it is electrolyzed, the electrolyte consumed beingif necessary replaced. The metal situated in the vessel I.is recovered in a suitable manner, for example by scraping it oil! the walls of the vessel, is purified by steps such as washing and vessel I is again made ready for electrolysis.

When employing apparatus according to Figures 2, 3 and 4, it is possible for example to cool the branch of the upper vessel I and by carefully introducing salt melt to produce a stopper-like closure, vessel I being thereupon charged to the necessary degree with the electrolyte and-electrolyzed. After deposition of a sumcient quantity of metal, the salt stopper in the branch piece is melted by the application of heat, and

the melt is drawn off into the underlying vessel II, any metal in the electrolyte being retained by the sieve provided in the branch or in the interposed perforated drum. When employing a perforated drum, it is also possible if desired, to

for the electrolysis by suspending the anode, is

moved into the upper position and is electrolyzed.

What I claim is:

1. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improvement which comprises carrying through the electrolysis in a plurality of vessels by first effecting such electrolysis in'one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to another vessel before any substantial cooling may take place where it is further electrolyzed, recovering the metal left in said first mentioned vessel, and then transferring the molten electrolyte after a substantial quantity of metal has been deposited in said second mentioned vessel but before the deposited metal may cause bridging and other electrolytic disturbances, to another vessel before any substantial cooling may take place, where the electrolysis is continued.

2. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improvementwhich comprises carrying through the electrolysis in a plurality of vesselsby first effecting such electrolysis in one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to another vessel before any substantial cooling may take place, adding fresh electrolyte to the electrolyte in said second mentioned vessel, continuing the electrolysis in said second mentioned vessel, recovering the metal left in said first mentioned vessel, and then transferring the molten electrolyte after a substantial quantity of metal has been deposited in said second mentioned vessel but before the -deposited metal may cause bridging and other electrolytic disturbances, to another vessel before any substantial cooling may take place, where the electrolysis is continued.

3. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improvement which comprises carrying through the electrolysis in a plurality of vessels by first effecting such electrolysis in one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to another vessel before any substanticn cooling may take place, adding fresh electrolyte to the electrolyte in said second mentioned vessel, continuing the electrolysis in said second mentioned vessel, then transferring the molten electrolyte after a substantial quantity of metal has been deposited in said second mentioned vessel but before the deposited metal may cause bridging and other electrolytic disturbances, to another vessel before any substantial cooling may take place, adding fresh electrolyte and continuing the electrolysis in said vessel.

4. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improvement which comprises carrying through the electrolysis in two vessels by first eflecting such electrolysis in one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to the second vessel before any substantial cooling may take place where it is further electrolyzed, recovering the metal left in the first vessel and transferring the molten electrolyte after deposition of a substantial quantity of metal in said second vessel but before the deposited metal may cause bridging and other electrolytic disturbances back to said first vessel where the electrolysis is continued.

5. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improve-V ment which comprises carrying through the electrolysis in a plurality of vessels by first ellecting such electrolysis in one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to another vessel before any substantial cooling may take place where it is further electrolyzed while retaining themetal deposited in said first vessel, recovering the metal left in said first mentioned vessel, and then transferring the molten electrolyte after a substantial quantity of metal has been deposited in said second mentioned vessel but before the deposited metal may cause bridging and other electrolytic disturbances, to another vessel before any substantial cooling may take place, where the electrolysis is continued.

, 6. In a process for the production of metals by the electrolysis of molten metal salts wherein the metals are deposited on the cathode in a substantially non-coherent form, the improvement which comprises carrying through the electrolysis in a plurality of vessels by first efiecting such electrolysis in one vessel, then after deposition of a substantial quantity of metal but before the deposited metal may cause bridging and other electrolytic disturbances transferring the molten electrolyte to another vessel before any substantial cooling may take place where it is further electrolyzed while straining out the metal particles in such electrolyte, recovering the metal left in said first mentioned vessel, and then transferring the molten electrolyte after a substantial quantity of metal has been deposited in said second mentioned. vessel but before the deposited metal may cause bridging and other electrolytic disturbances, to another vessel before any substantial cooling may take place, where the electrolysis is continued. v

' GUSTAV JAEGER. 

